This invention relates to a radio network controller, a mobile communications system, and an operation control method thereof and, in particularly, to a switching method in a protocol processing portion of the radio network controller for use in a wideband-code division multiple access (W-CDMA) communications system.
The W-CDMA communications system, which is defined by a 3rd generation partnership project (3GPP) as a world standard of mobile communications systems, comprises a radio network controller (RNC). The radio network controller (RNC) has, as one of functions, a protocol processing for processing user data in a radio interface.
The radio network controller (RNC) comprises a plurality of protocol processing portions. It will be assumed that a particular protocol processing portion is subjected to firmware renewal or hardware renewal. In this event, there is a method of renewing the particular protocol processing portion by putting the particular protocol processing portion into a blockade state so as to do not receive a new call. However, this method is disadvantageous in that it takes a long time at work because it is necessary to wait for completion of a call during communications.
There is another method of forcibly turning a call for the particular protocol processing portion out. However, this method is disadvantageous in that it results in degradation of service quality for the call during communications.
Furthermore, according to the 3GPP, there is a processing called relocation as a processing for handing over the protocol processing. However, the relocation processing is disadvantageous in that a user equipment (UE) serving as a mobile communication terminal must consciously operate.
Various other techniques related to this invention are already known. By way of example, United States Patent Application Publication No. US 2004/0009773A1 discloses “MOBILE COMMUNICATION SYSTEM AND OPERATION CONTROL METHOD THEREOF.” According to US 2004/0009773A1, an ATM (Asynchronous Transfer Mode) network used in a radio access network (RNA) is IP (Internet Protocol)-networked. The radio access network (RAN) comprises a C plane processing device for signaling processing and a plurality of U plane processing devices for user data processing which are provided in a physically separated manner. With the U plane processing devices, a backup U plane processing device is prepared independently from one or more active U plane processing devices. When congestion occurs in the active U plate processing device, part of processing is switched to and inherited by the backup U plane processing device. However, the technique disclosed in US 2004/0009773A1 intends to perform load distribution processing in order to expel processing from concentrating and does not intend to renew firmware or hardware of a particular protocol processing portion by completely putting the particular protocol processing portion into a blockade state.
Furthermore, Japanese Unexamined Patent Publication of Tokkai No. Hei 5-244,225 or JP-A 5-244255 discloses “UNINTERRUPTIBLE SYSTEM CHANGEOVER METHOD” to attain the changeover between an active system and a standby (backup) system without interruption during communication by allowing both the active system and the standby (backup) system to take over a protocol processing state with each other during the changeover between the active system and the standby (backup) system. However, the technique disclosed in JP-A 5-244255 does not give consideration to application to the protocol processing portion of the radio network controller (RNC) in the mobile communication system. More specifically, the protocol processing portion of the radio network controller (RNC) in the mobile communication system includes a function for performing a ciphering processing on user data. On carrying out firmware renewal or hardware renewal of the protocol processing portion in the radio network controller (RNC), it is necessary to changeover between the active system and the standby (backup) system in consideration of ciphering parameter which is a parameter for the ciphering processing. Inasmuch as the technique disclosed in JP-A 5-244255 does not intend to apply to the mobile communication system, the technique disclosed in JP-A 5-244255 cannot really be applied to in a case of carrying out the firmware renewal or the hardware renewal of the protocol processing portion in the radio network controller (RNC).
U.S. Pat. No. 6,668,170 issued to Costa et al. discloses “MOBILE RADIO TELECOMMUNICATIONS SYSTEM WITH SYNCHRONIZED HANDOVER.” According to Costa et al., in a mobile radio network such as the Universal Mobile Telephone System, for handover or relocation of control of a mobile from a serving RNC (Radio Network Controller) to a target RNC, the target RNC sends a request to the serving RNC over the lur link, and the serving RNC returns frame timing information. The target RNC synchronizes the user plane with the serving RNC for this uplink, so that both controllers are also able to send the same packets in synchronism. The core network can suppress the duplicated packet. However, Costa et al. merely discloses the handover or relocation of control of the mobile from the serving RNC to the target RNC, Costa et al. neither discloses nor teaches handover of ciphering parameter from a protocol processing portion to another protocol processing portion in the radio network controller (RNC).
Japanese Unexamined Patent Publication of Tokkai No. 2001-144,806 or JP-A 2001-144806 discloses “NETWORK ADDRESS TAKEOVER METHOD FOR DUPLEX SYSTEM, DUPLEX SYSTEM HAVING NETWORK ADDRESS TAKEOVER FUNCTION AND RECORDING MEDIUM” to provide a network address takeover (handover) method of a duplex system. However, JP-A2001-144806 merely discloses the takeover (handover) of the network address, JP-A 2001-144806 neither discloses nor teaches handover of ciphering parameter from a protocol processing portion to another protocol processing portion in the radio network controller (RNC).